1. Technical Field
The invention disclosed herein broadly relates to telephone communications and more particularly relates to telephone interconnection circuits.
2. Background Art
In conventional telephone network operations, the billing process does not start until the called phone goes off hook. When a human answers the called phone, his response is slow enough so as to enable the billing process to be completed before the human begins speaking his answer on the phone. However, in the data/auto answer mode for modems, the answer tone generated by the answering modem is too fast to allow the billing process of the telphone company to be completed. Therefore, in order to allow the billing process to be completed, the FCC has required in its Part 68 Convention, a 2.7 second delay before an auto answer modem can provide an answer tone in responding to a call.
This creates a problem for a human answering a telephone which is to be in alternately a voice or a data mode, since the human must wait 2.7 seconds before he is able to hear or transmit voice signals.
In the prior art, no provision was provided for selectively providing the billing delay for auto answer or alternately no billing delay for human voice answering.
Still another provision of the FCC Part 68 is a tone overload detector which must be associated with auto answering modems. The tone overload detector will interrupt the connection between the modem and the telephone network line if answer tones have a voltage greater than a predetermined amplitude. However, if a human answers the telephone, his voice frequency is within the range of the tones to which the tone overload detector is sensitive. Therefore, it is conceivable that the human voice could trip the tone overload detector, thereby interrupting the connection with the telephone network. Therefore it is also desirable to provide a means for selectively disabling the tone overload detector when a human will be answering the telephone.